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Fabrication and Analysis of Mechanical Properties of Frp Composites

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Fabrication and Analysis of Mechanical Properties of Frp Composites
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  International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 8, August (2014), pp. 49-56 © IAEME   49 FABRICATION AND ANALYSIS OF MECHANICAL PROPERTIES OF FRP COMPOSITES Dr. M.AnandaRao 1 , Dr. K.Vijaya Kumar Reddy 2 , T.Seshaiah 3   1 Professor, Department of Mechanical Engineering, MLR institute of Technolgy, Dundigal, Hyderabad. 2 Professor, Department of Mechanical Engineering, JNTU College of Engineering, Hyderabad. 3 Associate Professor, Department of Mechanical Engineering, QIS College of Engineering & Technology, Ongole. ABSTRACT The main objective of this paper is fabrication and analysis of mechanical properties of FRP composites, comparison of mechanical properties of two test pieces fabricated with and without mixing iron flakes. A Test piece with Glass fibers & Epoxy resin and another test piece with the Glass fiber and Epoxy Resin mixed with iron flakes are fabricated and various mechanical testing is done on both the test pieces and the results have to be compared. The fabrication is done using the dimensions according to the ISO standard. The test pieces are tested using Universal Testing Machine. The main purpose of the paper is to determine the best FRP composite from the two test pieces by comparing the tensile strength, flexural strength and shear strength. Keywords: Fabrication, Analysis, FRP Composite, Glass Fiber, Epoxy Resin, Iron Flakes. 1.0   INTRODUCTION Composite materials are materials made from two or more constituent materials with significantly different physical or chemical properties, that when combined, produce a material with characteristics different from the individual components. Composite structures, used to meet the demand for lightweight, high strength/stiffness and corrosion-resistant materials in domestic appliances, aircraft industries and fields of engineering composites, have been one of the materials used for repairing the existing structures owing to its superior mechanical properties. Applications of composite materials have been extended to various fields, including aerospace structures, automobiles and robot systems.   INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 5, Issue 8, August (2014), pp. 49-56 © IAEME: www.iaeme.com/IJMET.asp Journal Impact Factor (2014): 7.5377 (Calculated by GISI) www.jifactor.com   IJMET   © I A E M E    International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 8, August (2014), pp. 49-56 © IAEME   50 Composite materials are not homogeneous. Their properties are dependent on many factors, the most important of which are the type of fiber, quantity of fiber (as volume fraction) and the configuration of the reinforcement.They are generally completely elastic up to failure and exhibit neither a yield point nor a region of plasticity. The properties of composites are dependent on the properties of the fiber and the matrix, the proportion of each and the configuration of the fibers. If all the fibers are aligned in one direction then the composite relatively stiff and strong in that direction, but in the transverse direction it has low modulus and low strength. When a unidirectional composite is tested at a small angle from the fiber axis, there is a considerable reduction in strength. A similar but less significant effect occurs with the tensile modulus. FR composites materials offer a combination of strength and elasticity that are better than conventional metallic materials. Composites are superior because of their low specific-gravities, strength-weight ratios. Structural materials such as steel and aluminum alloys are considered isotropic since they exhibit nearly equal properties irrespective of the direction of measurement. Composites consist of two or more phases that are usually processed separately and then bonded, resulting in properties that are different from those of either of the component materials. For many years glass composites have had a distinct strength to weight advantage. Although the rapid evolution of carbon and aramid fibers has gained advantages, glass composite products have still prevailed in certain applications. Resin is a generic term used to designate the polymer, polymer precursor material, and/or mixture or formulation thereof with various additives or chemically reactive components. The resin, its chemical composition and physical properties, fundamentally affect the processing, fabrication and ultimate properties of composite materials. Fillers are inert substances added to reduce the resin cost and/or improve its physical properties, viz., hardness, stiffness and impact strength. Commonly used fillers are iron flakes, calcium carbonate, hydrated alumina and clay. 2.0   FABRICATION OF FRP COMPOSITES FRP fabrication consists of suitably combining reinforcement material (glass fiber or carbon fiber) with a matrix material (resin) by a suitable production, process and of curing the resulting moulding into the required product. Fabrication Techniques of composites are (i) making the product by moulding it into shape(ii) making the product by winding the filaments(iii)Making the product by continuous on line production methods (iv)Making the product by centrifugal casting. Hand Lay-up Process is used for the fabrication of the test pieces. 2.1 PROCEDURE OF MAKING THE TEST PIECES A mould is prepared for fabrication of the test pieces. The process used is Hand Lay-up process. The mould should be in such a way that the thickness of the test pieces should be 6-7mm as per the ISO standards. After preparing the mould, 400gms of Epoxy resin should taken and mixed thoroughly with 5 % (20gms) of Hardener. LapoxL12 is the type of epoxy resin used and K6 is the hardener which is a low viscosity room temperature curing liquid hardener. It is common employed for hand lay up applications. The choice of hardener depends on the processing method to be used and on the properties required of the cured composite. Hardener K6 being rather reactive, it gives a short pot life and rapid cure at normal ambient temperatures. Laminates can be subjected to operating temperatures of 100 °C. Test Piece 1 ( Epoxy Resin with Glass Fiber): In a mixing jar or pot, 400gms of Epoxy resin and 20gms of K6 hardener as per the ISO standards is taken. The mixture should be mixed thoroughly with a long stick and a mask should be weared while mixing the resin as Epoxy is very harmful for  International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 8, August (2014), pp. 49-56 © IAEME   51 health if it is inhaled. It should be mixed completely so that the resin is uniform in every part of the mixture. Before mixing it, the glass fibers should cut and should be kept ready. The type of glass fiber used is E-Glass. Four type of glass fiber cloth or mat, i.e., Glass, Roving, CSM (Chopped Strand Mat) and Unidirectional (UD), are used for fabrication. As per ISO Standard and the requirement of 6mm thickness, 8 pieces of Glass type, 7 pieces of Roving type, 1 & half pieces of CSM type and 2 pieces of Unidirectional type are taken. Glass type is found to have 400 gms in weight, Roving type is found to have 440 gms in weight, Unidirectional is found to have 90 gms in weight and CSM is found to have 40 gms in weight. The four types of Glass fibers should be cut with a dimension of 250*200mm (or) 25*20cm. These glass fibers types should be placed in a specific order as per ISO standards. The order is as follows: Glass   Roving   Glass   Roving   CSM   Glass   Roving   UD   Glass   Roving   UD   Glass   Roving   CSM   Glass   Roving   Glass  Roving   Glass. Now the mould is cleaned with Waxpol so that the epoxy resin will not stick to the mould. After applying Waxpol, the mould surface should be cleaned thoroughly by fresh cotton. Then PVA should be applied to the surface of the mould so that the test piece can be easily removed without any loss of material. After applying PVA, it should be kept untouched for 15-20 mins, so that the PVA is fully dried. After that the Epoxy resin mixture should be applied on the surface of the mould with the dimensions of 25*20cm. Place the Glass type on it first and then Roving cloth & the above order should be followed. After Glass mat, apply the resin again on it and with the help of a roller, the air bubbles or irregularities should be avoided. This process is continued till the last Glass type (see the above order). After the last glass type is placed, the epoxy resin is applied on it and quickly the mould is closed. It will take nearly a whole day for this test piece to dry completely. Next day when the test piece is fully dried, we have to keep it for curing for 7-8 days at room temperature. Only after curing, we should cut our test piece for testing with required dimensions according to the ISO Standards. Test Piece 2 ( Epoxy resin with Glass Fibers with Iron Flakes):- The above is the procedure for the Test piece FRP of Epoxy Resin and Glass Fibers. Second Test piece is FRP of Epoxy resin with Glass Fibers with Iron Flakes. In a mixing jar or pot, 400gms of Epoxy resin and 20gms of K6 hardener and 40gms of Iron Flakes as per the ISO standards is taken. The mixture should be mixed thoroughly with a long stick and a mask should be weared while mixing the resin as Epoxy is very harmful for health if it is inhaled. It should be mixed completely so that the resin is uniform in every part of the mixture. Before mixing it, the glass fibers should cut and should be kept ready. The type of glass fiber used is E-Glass. Four type of glass fiber cloth or mat, i.e., Glass, Roving, CSM (Chopped Strand Mat) and Unidirectional (UD), are used for fabrication. As per ISO Standard and the requirement of 6mm thickness, 8 pieces of Glass type, 7 pieces of Roving type, 1 & half pieces of CSM type and 2 pieces of Unidirectional type are taken. Glass type is found to have 400 gms in weight, Roving type is found to have 440 gms in weight, Unidirectional is found to have 90 gms in weight and CSM is found to have 40 gms in weight. The four types of Glass fibers should be cut with a dimension of 250*200mm (or) 25*20cm. These glass fibers types should be placed in a specific order as per ISO standards. The order is as follows: Glass   Roving   Glass   Roving   CSM   Glass   Roving   UD   Glass   Roving   UD   Glass   Roving   CSM   Glass   Roving   Glass  Roving   Glass.  International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 8, August (2014), pp. 49-56 © IAEME   52 Now the mould is cleaned with Waxpol so that the epoxy resin will not stick to the mould. After applying Waxpol, the mould surface should be cleaned thoroughly by fresh cotton. Then PVA should be applied to the surface of the mould so that the test piece can be easily removed without any loss of material. After applying PVA, it should be kept untouched for 15-20 mins, so that the PVA is fully dried. After that the Epoxy resin mixture should be applied on the surface of the mould with the dimensions of 25*20cm. Place the Glass type on it first and then Roving cloth & the above order should be followed. After Glass mat, apply the resin again on it and with the help of a roller, the air bubbles or irregularities should be avoided. This process is continued till the last Glass type (see the above order). After the last glass type is placed, the epoxy resin is applied on it and quickly the mould is closed. It will take nearly a whole day for this test piece to dry completely. Next day when the test piece is fully dried, we have to keep it for curing for 7-8 days at room temperature. Only after curing, we should cut our test piece for testing with required dimensions. . 3.0   ANALYSIS OF MECHANICAL PROPERTIES OF FRP COMPOSITES: The performance of a material is judged by its properties and behaviour under tensile, flexural and shear constraints. These properties are also known as static mechanical properties of the materials. Tensile Properties of Test Piece 1   Specimen for Testing Tensile Strength The Tensile Strength Testing was done at CIPET, Hyderabad. The Input or the dimension of test piece & Gauge Length is shown in below table: Thickness Width Gauge Length Units mm mm mm Epoxy & Glass Fibers (Test Piece 1) 7.1 22 150
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